城市污泥对杨树幼苗光合生理特性的影响

Effects of Municipal Sewage Sludge on Photosynthetic Characteristics in Poplar Seedlings

城市污泥是指城市生活污水、工业废水处理过程中产生的固体废弃物。近些年,随着城市化迅速发展和人口的急剧增加,每年排放的污泥量在不断增加（马娜等,2004）。如何合理、安全有效地处置数量巨大的污泥已成为紧迫的任务。城市污泥的资源化利用是减少二次污染、实现资源可持续利用的有效方法之一,而污泥的园林或林地利用不失为一种最经济、最普遍的处理方法。

A potting experiment in greenhouse was conducted to study the effects of municipal sewage sludge（MSS） on the photosynthetic parameters,including net photosynthesis rate（Pn）、transpiration rate（Tr）、chlorophyll content and nitrogen content in leaves of poplar seedlings（Populus × euramericana＇Guariento＇）.Six treatments were set,i.e.,four different dosage MSS as follows：30 t.hm-2（LS）,60 t.hm-2（MS）,90 t.hm-2（HS）,120 t.hm-2（SS）,and inorganic compound fertilizer 0.45t.hm-2（F） and control（without application of sewage sludge and inorganic fertilizer）.The results showed that the Pn and Tr in treatment F were greatest with 22.59% and 3.57% higher than those of control treatment,respectively.With the increase of MSS dosage,the chlorophyll and nitrogen contents in leaves tended to increased,but the Pn and Tr had a decreased.Treatments LS,MS,SH and SS treatment led to a decrease in Pn by 13.10% ～ 37.03% and 29.11% ～ 48.63%,and the Tr by 14.31% ～ 31.38% and 17.27% ～ 33.74%,respectively,compared with control and F treatment.Furthermore,the stomatal limitation（Ls） decreased with Pn decrease,suggesting that the decrease of Pn might be mainly caused by nonstomatal limitation.Our results suggested that the above changes in photosynthetic and the related physiological characteristics of poplar seedlings might be induced by the interaction between nutrition level and heavy metal in MSS.